Valve mechanism of internal-combustion engines



l 1. 25mm. y

`VALVE MECHANJSIVI 0F INTERNAL COMBUSTION ENGINES.

APPLIQATION FILED SEPT. 3, 1918.

lacented Jan 3, 1922.

3 SHEETS-SHEET I.

. y J. ZEITLIN. VALVE MECHANISM 0F INTERNAL COMBUSTION ENGINES.

APPLICATION FILED SEPT. 3) IBIB.

Patented Jan. 3,1922'.

3 SHEETS-SHEET 2- z 7 o'sgv or 54 n reda( J. ZEIILIN. VALVE MECHANISM oF INTERNAL comusloN ENGINES.

APPLICATION FILED SE-PT- 3. |918.

2. .2 93 1T 3,m n dw w3 .m 3 nw P Ill Q .........H.|. o 1 F v rosErn zEI'TLIN, or LoNDoN, ENGLAND.

VALVEMECHANISM or INTERNAL-COMBUSTION ENGINES.

` Specification of Letters Patent. Pateted Jan. 3, 1922.

Application filed September-3, 1918. Serial No. 252,490.`

(GRANTED UNDER THE raovrsroNs or '111s Aer or maken a, 1921, 41 sur. 1..., 1313.)l

To all whom t may concern.:

Be it known that I, JOSEPH ZEITLIN, a subject of the King of England, residing in London, En land, have invented certain new and useful Improvements in' the Valve Mechanism of Internal-Combustion En-` gines, (for which I have filed an application in England, Oct. 18, 1916, Patent No. 125,664,) of which the following is a specifi.- cation. v

This invention relates to means for varying'the amount and character of the mixture which is compressed in a constant compression space of an internal combustion engine, particularly of the rotating cylinder engine type.

The invention has for its particular object to improve the performance of internal combustion engines used for aeronauti 20 cal purposes, as these engines, more than any other, suer from large variations in the atmospheric conditions at different altitudes, with corresponding variations in the density and also the constitution of the air. Thus, at higher altitudes, for the same result a greater volume of air is required by reason of the diminished density and a still greater volume is required by reason of the smaller proportion of oxygen in the atmosphere at high altitudes. v

Further, the means which are ado ted for improving the economy and power o the engine under the above conditions also provide aE simple method of varying thespeed of the engine and of facilitating the starting of the same.

The invention relates to engines in which the cams for loperating the exhaust valves in the normal working of the engines are placed sideby side on a shaft driven by the engine and in which in addition to these cams, means are provided by which these valves'can be opened during a controllable portion of the compression stroke to permit of the expulsion of part of the' contents of the cylinders and thereby lessen the power developed by the engine when flying at low altitudes or when for other reasons a reduc,- tion in power is desirable.

Forvthe purpose of opening the exhaust valves during the compression stroke an arcshaped arm is pivoted' at a' fixed point, the arc being slightly eccentric to the shaft on which are placed the cams for the'normal operation of the exhaust valves. The pivoted arm can be adjusted between two limiting positions, in one of which it has no effect, the opening and closing of the valves being determined entirely by the usual cams,

-while in the other limiting position the pivoted arm is arranged to open the valves durmg the compression stroke, so as to leave in the cylinders only suiicient charge to enable the engine to revolve.

The pivoted cam arm co-operates with a series of bell crank levers, fulcrumed upon the rotating ,part of the engine.' One arm of each of these levers is preferably provided with a roller co-operating directly with the pivoted cam. These arms are thus all in the same plane. The other arms, on the contrary, are in diii'erent planes corresponding with the planes of the ordinary actuating cams of the exhaust valves of the engine, and are arranged to interpose, with or without rollers, between these cams and the valvetap-pets.

It will be obvious that for intermediate positions of the pivoted cam the period, as'

the pivoted cam or its equivalent will be revolved and means provided for advancing it towards or withdrawing it from the cooperating stationary bell'cranlz arms within the working limits.

In the accompanying drawings, Fig. l is an end view o f an example of a construction according to the invention for operating the exhaust valves of an internal combustion engine with rotary cylinders; Fig. 2 is a vertical section on]- the line' 2--2'of Fig.A 1. Fig. 3 shows a hand operated de vice for controlling the position of the pivoted cam arm whichV determines the opening of the exhaust valves during the compres sion stroke, and Fig. 4 is a slightly modified arrangement for this purpose.

Fig. 5 is an end view and Fig. 6 a section on the line 6-6 of Fig. 5 of a modied disposition of the pivoted cam and the levers operating the exhaust valves. Fig. 7 is an end view and Fig. 8 a section on the line 8-#8 `of Fig. 7 of a construction adapted for an internal combustion engine with stationary 'cylinders y Referring to Figs. 1 and 2, which represent a 7-cylinder engine, on the shaft 1 `driven from the engine shaft by meansof sun and planet wheels 2, 3, 4, 5 are seven calnldiscs 6 vdisposed in parallel planes on the shaft 1. -The cam swell 7 of the centrally disposed cam is shown in engagement with one arm 8 of a bell crank vlever 8, 9 attached to a rocking shaft 10; the arm 9 carries a roller 11 and it will. be seen that the tappet rod 12 1s operated to open the exhaust valve towhich it is connected, either when the cam swell 7 is iii/engagement with the arm 8 of thev bell crank lever, or when the rolle'r 11 of the same lever is 'forcedt inwards by contact with a stationary cam Qarm 13 pivoted at 14.

The cams 7 openthe exhaust valves in the usual manner during the exhaust stroke, the

pivoted cam 13 is adapted to open the valves during a portion of the compression stroke, the time during which a valve is opened and the extent of the opening depending upon the 'position imparted to; the.. arm 13 by a sliding` wedge-shaped member 15. Limiting positions of the arm are determined by a slot 16 at its free end engaging with a pin 17 secured to the stationary framework.l In the most advanced position of the cam arm, the roller attached to each bell crank lever is forced inwards during a certain part of its travel past the cam 13 through a distance represented by the difference in the radii of the circles 18 and 19 andy opens the corn responding exhaust valve to an equivalent extent. The contour of the arm is such that the valve is only opened for a portion of the compression stroke and the maximum Y opening is slightly less than the opening effected by the cams 6. In the extreme outward position of the free end of the arm, the exhaust valves are not opened during the compression stroke. 1 Fig. 3 shows an arangement by which the position of the arm 13 is adjusted Yto suit the requirements as regardsspeed, power or altitude., r

Assuming that the engine is fitted on an aircraft, a dial 20 is marked Yin thousands of feet or barometric pressure altitude, a

.screw threaded rod 21` is turned by a hand wheel 22 until a pointer 23 gearing with ,the screw thread on the rod 21 points to the altitude attained. 'A flexible wire cable 24 is connected tothe rod 21 and rotates withr it the threaded end 25 of the flexible cable .turning in the nut 26 causes -the wedge 'shaped member 15 to slide to and fro in the stroke, but not in any way to interfere with. the operation of these .valves during the exhauststroke of the engine. When flying at low'levels where the denslty of the air and the proportion of oxygen are both greater, the pivoted arm wouldl ordinarily be adjusted to open the exhaustv valve during about 40 per cent of the compression stroke While for slow running the valve is kept open forA longer periods; -as the altitude attained increased, the pilot would adjust the sliding member 1 5, so as to reduce the extent of opening, untll at the highest altitude, of* about 10,000 feet or more the pivoted arm would be inoperative and the maximum amount of air retained to mix with the petrol. In the usual practice, the speed falls off at high altitudes on account of the lower power developed,..in spite of the lessened resistance due to the rarer atmosphere. In the system according to the invention, as the power is maintained atapproximately constant value, Ithespeed increases with the height gained. It is found in practice that the longer the exhaust valves are opened the richer is the resultant mixture, showing that it is mainly air and very little petrol which escapes through the' `o f the altitude at which he may be iying.

The screw threaded rod 21 may be automatlcally operated to maintain a predetermined speed by means of a centrifugal gov? ernor which in accordance with the speed of rotation brings` the one` or other of a pair of bevel wheels on a sliding sleeve to impart motion ,through suitable gearing to the yond the predetermined amount causing the pivoted camarm to be moved inwards to itsv Y voperative position and a decrease of, speed causmg the arm to `be withdrawn so as to lessen the period duringwhich the exhaust valves are open.` If this arran ement is threaded rod 21, an increase of speed besliding wedge 15 is replwed by a cranked lever 28, which rotates a cam 29 to adjust the position of the cam arm-13. 4

-In the construction shown in Figs.` 5 and 6 the arms 8', and 9 are differently disposed on the rocking shaft 10 and the cam arm 13 is arranged to contact ywith the inner instead of with the outer parts of the peripheries V'of therollers 11. In this arrangement the free enel of the arm `is moved outwards in order to open the valves for a longer period or to a greater extent.

While this construction reduces the dimensions of the parts and the velocity at.

which the rollers engage with the stationary arm, the inertia ofl the moving parts is not so Well balanced as in the construction illustrated in Figs. 1 and 2.

Figs. 7 and 8 illustrate a construction according to the invention .adapted for cngines with stationary cylinders. The pivoted cam arm rotates with the engine shaft and is moved outwards to engage with the rollers 11 of the arms 91 secured to the rocking shafts 10 and thereby to open the exhaust valves on the compression stroke. The bearings of the rocking shafts are fixed in the stationary crank case. In the Yexample shown, the position of the arm 13 is adjusted'by means of a rod '30, pivoted at 31, the free end of the rod terminatingin a fork 32 carrying a nut engaging with, a screw thread ofA a bar one end of which is pivoted in a ball and socket joint 33, while the other end is attached to thelexi ble cable rotated by a hand Wheel as shown in Fig. 3.

The rod is forked at 34 to'engage with the collars of a ta ered sleeve 36, the

forked members of W ich,` asthe sleeve v slides to thev left, Ibring the cam `arm into en agement vWith the rollers 11.

aving thus described the -nature of the said invention and the .best means I lmow of carrying the same into practical eect, I claim z- In a multiple cylinder internal combustion engine, a crank shaft, cam disks arranged in parallel planes on the crank shaft,

rocking shafts, two-armed levers on said rocking shaft, one arm of veach lever being adapted to engage with one of said cam disks and co-operative with a cylinder `exhaust valve to open the latter for the discharge of the burnt gases and the other arm of the lever. carrying a roller, a cam lever comprising a pivoted arc-shaped arm `slightly eccentric to and shiftable into the path of the vsaid roller, an altitude index, means for setting said index, and means associated With said index setting means and said arc-shaped arm to shift the latterinto the path. of said roller when said index setting means is' actuated.

JOSEPH ZEITLIN. 

